Ramscar et al (2014)1 claim that Cognitive Aging is “a myth” because slowing of all decisions is a key behavioural marker of mental changes in old age2 but occurs only because accumulation of information over a lifetime slows retrieval of data to support any decision. This feel-good news that slowing of decisions on all tasks is not a defining symptom of progressive failure but an honourable distinction of an age-stocked mind has eagerly excited the media (Telegraph; Guardian; BBC World Service , New York Times), but not researchers on cognitive aging.

The Ramscar model seems to derive from the earlier Homer Simpson model: “Every time I learn something new it pushes something out”. The Simpson model makes no prediction for decision speed because it posits finite data capacity beyond which no increment, and so no further slowing, can occur. In this respect it is more elegant than…